The Teenage Mutant Ninja Turtles action figures swept the toy nation around 1989-1990.  Definitely one of the most odd creations, mixing mutated turtles and ninjas, but it worked.  Leonardo, Donatello, Michaelangelo, and Raphael, lead by their mutant rat leader Splinter, doing battle with the evil Shredder and his army, was a story that lead to movies and years worth of action figures.